As you can see, jobs have been expanding at the low and
high-skill levels. Middle-skill jobs have actually contracted.

"The decline in the share of middle-skill jobs has largely been
driven by technological advancements and outsourcing of jobs
overseas," Aleman and Khan explain. "Middle-skill jobs are
classified as those that require some routine set of tasks, while
high- and low-skill jobs perform non-routine tasks. Workers in
routine professions have been increasingly displaced by the
widespread use of computers."

Someone has to make those computers.

"With the increase in technology, the demand for high-skill
workers continues to expand," the economists write.

It may be counterintuitive that low-skill jobs aren't being
replaced by robots. But the world just isn't that simple.

"High-skill jobs are typically those that require some
post-secondary education, while low- skill occupations, including
food preparation and building and grounds maintenance require
face- to-face interaction," they add. "These factors make these
functions very difficult to outsource or automate."

Among other things, this has implications for inequality.

"Occupations that are high-skill are those that have an annual
wage greater than $60,000," they note. "The top occupations in
this category include management, computer and mathematical,
legal, and architecture and engineering. Middle-skill occupations
are jobs that bring home an annual median wage of $25,000 to
$59,000, while low- skill occupations are jobs with an annual
median wage of less than $25,000."